Reinforced cell closure



Oct. 30, 1962 R. L- cHENK, JR 3,061,660

REINFORCED CELL CLOSURE Filed Aug. 4, 1960 i, & m

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fM (MW/ A rrow/5r ilnited S tates York Filed Aug. 4, 1960, Ser. No.47,407 4 Claims. (Cl. 136-133) This invention relates to a cell closurefor a cylindrical galvanic cell, and more particularly, it relates to areinforcement ring for use with such a cell closure.

United States patent application, Serial No. 774,931, filed November 19,1958 in the names of R. Carmichael et al. discloses an excellent closurefor cylindrical alkaline galvanic cells which is extremely resistant tocaustic creepage. The disclosed cell closure comprises an annular gasketof a hard, di-electric, plastic-like material which is resistant tocold-flow and a metallic container cover, the gasket being interposedbetween the cell container wall and the edge of the cell cover insupportingrelation with the cell cover. The actual sealing is effectedby radially compressing the gasket between the container and the cellcover under a high radial force. After the compressive force is removedfrom the container, the gasket will exert a radial compressive forceoutwardly against the container which is substantially equivalent to,but not greater than, the yield strength of the metal of which thecontainer is made.

in the preferred method disclosed to accomplish such radial sealing,that is, by forcing the container with the gasket and cover in placethrough a reducing or sizing die, a shoulder must be provided at theopen end of the container to support the seal gasket during sealing.

Unfortunately, the use of a container with a shoulder at the toppresents a number of difficulties during the manufacturing process.Namely, it prevents the cells from being rolled uniformly from stationto station during manufacture and such a container is diflicult toproduce. Extreme control of the container forming equipment is necessaryto provide a sharply defined step and yet not form it so deeply that thecontainer wall is weakened.

Accordingly, the principal object of the invention is to provide aradially sealed galvanic cell wherein a straight sided container may beemployed.

The principal object of the invention is accomplished by a galvanic cellwherein the cell closure comprises an annular gasket of a harddi-electric material which is resistant to cold flow interposed andradially sealed between the container wall and a two member cell cover,one member of which is a washer type lid which imparts resiliency to theback up support for the gasket when it is radially sealed; the top ofthe outside of the container being provided with a reinforcement ring.

The term cold-flow as used herein and in the appended claims, refers tothe gradual deformation of a material that occurs when that material issubjected to a constant load at room temperature. Materials which deformvery little or only when large forces are applied and which do notcontinue to deform or creep when the force is applied for a considerablelength of time are said to have good cold flow characteristics.

Additionally, the seal gasket used must be made from a material whichwill not be attacked by the corrosive electrolyte of the cell and whichhas good di-electric properties as well, the gasket serving to insulatethe positively and negatively charged parts of the cell. Of course, thematerial must be one generally characterized by its high compressive andshear strength and one capable of withstanding large stresses without atendency to cold flow.

atent ice Nylon, a polymer of hexamethylene diammonium adipate, is ahard plastic composition that has been found to be a suitable materialfor use in practice of the invention. A nylon plastic sold under thetrademark Zytel is the preferred material.

The invention will be more readily understood by reference to theaccompanying drawing wherein:

FIG. 1 is a front elevation view, partially in section, of the topportion of a cylindrical galvanic cell which shows the seal assembly ofthe invention prior to being radially compressed; and

FIG. 2 is a view'of the cell of FIG. 1 after it has been radiallysealed.

Referring now to the drawing, and particularly FIG. 1, the cell closureof the invention comprises an annular generally L shaped hard nylongasket 10 which is provided with a flange 12 to support the gasket 10 onthe top of the cylindrical metal cell container 14 and which isinterposed between said container 14 and a two member cell cover. Onemember of the cell cover is an annular generally U shaped ring 16,preferably made of nickel or nickel plated steel, and which has anintegral protruding cap 18 which receives the central electrode 19 ofthe cell and thereby serves as one terminal of the cell. The othermember of the cover is a metal washer 20, preferably made of steel orstainless steel, which resides in the U shaped portion of the firstcover member 16. The steel washer 20 gives back-up support when the cellis radially sealed, and provides resiliency to keep the seal tight. Ametal reinforcing ring 22 provided with an inward facing flange 24 and adependent flange 26, is provided over the top of the container Wall 14and adjacent the gasket flange 12 which supports the gasket 10 on thecontainer wall 14.

The actual radial sealing of the cell, as shown in FIG. 2, may beaccomplished in a number of ways, a typical way being by pushing orforcing the container 14, with the gasket 10, cover members 16 and 20and reinforcement ring 22 in place, through a sizing die so that thering 22 is reduced in diameter to the diameter of the unreinforcedportion of the container 14, thereby exerting a maximum radial sealcompressive force on the container 14. The deformation of the metalcontainer 14 by the sizing operation is permanent for any spring back ofthe container 14 after passing through the sizing die is prevented bythe reinforcement ring 22.

In order to test the effectiveness of the cell closure of the invention,29 D size alkaline cells were made with the cell closure. The cells wereovercharged, subjected to thermal shock, high humidity and then placedon shelf for a period of two years. Less than 10% of the cells showedany evidence of leakage and this was a minor degree. This testconclusively demonstrates the ability of the closure of the invention towithstand caustic creepage under abusive conditions.

I claim:

l. A closure for sealing a galvanic cell against electrolyte leakage;said galvanic cell comprising a cylindrical cupped metallic container ofuniform diameter and an electrolyte therein; said closure comprising anannular hard plastic gasket which is resistant to cold flow having aflange extending over the top of said container and which is interposedbetween said container and a two member cell cover; the first member ofsaid cover being an annular generally U shaped metal ring having anintegral centrally located protruding terminal cap and the second memberof said cover being a metal washer which resiliently resides in the Ushaped portion of said first cover member, and an external metalreinforcement ring encircling said container at its top which has adepending flange which presents a flush surface with said container walland an inwardly facing flange adjacent said flange on said gasket; saidgasket being in a state of radial compression between said container andsaid cover and exerting a radial force substantially equivalent to, butnot greater than, the yield strength of the metal of which saidcontainer is made.

'2. The closure of claim 1 wherein said gasket is gen- 'erally L shapedand made of hard nylon, said generally .U shaped ring is made of amaterial chosen from the group consisting of nickel and nickel platedsteel and said metal washer is made from a'material chosen from thegroup consisting of steel and stainless steel.

3 A sealed galvanic cell comprising a cylindrical cupped metalliccontainer of uniform diameter, said cell being sealed at the open end ofsaid cupped container by a closurewhich comprises an annular hardplastic gasket which is resistant to cold flow, having a flangeextending over the top of said cupped container and which is interposedbetween said container and a two member cell cover; the first member ofsaid cover being an annular generally U shaped metal ring having anintegral centrally located protruding terminal cap and the second memberof said cover being a metal washer which resiliently resides in the Ushaped portion of said first cover member, and an exterior metalreinforcement ring encircling said container at the top which has adepending flange which presents a flush surface with said container walland an inwardly facing flange adjacent said flange on said gasket; saidgasket being in a state of radial compression between said container andsaid cover and exerting a radial force substantially equivalent to, butnot greater than, the yield strength of the metal of which saidcontainer is made.

4. The sealed galvanic cell of claim 3 wherein said gasket is generallyL shaped and made of hard nylon, said generally LI shaped ring is madeof a material chosen from the group consisting of nickel and nickelplated steel and said metal washer is made of a material chosen from thegroup consisting of steel and stainless steel.

7 References Citedin the tile of this patent UNITED STATES PATENTS2,495,247 Friedman Jan. 24, 1950 2,541,931 McEachron Feb. 13, 19512,636,062 Colton Apr. 21, 1953

